To make cranberry puree: Cook cranberries and sugar in a saucepan over medium-high heat until cranberries pop open and blend easily, about 8 minutes. Let cool. Process in a blender until smooth, then strain through cheesecloth or a fine-mesh strainer. Puree can be stored in the refrigerator, covered, for up to 2 weeks.

To make lemongrass simple syrup: Combine sugar, 1 cup water, and lemongrass in a saucepan. Cook over medium-low heat until liquid becomes sticky, about 10 minutes. Let cool; strain and discard lemongrass. Simple syrup can be stored in the refrigerator for 1 month.

To assemble: Combine Stoli, Cointreau or Triple Sec, 3 tablespoons cranberry puree, 3 tablespoons lemongrass simple syrup, and lime juice. Working in batches, place into a shaker with ice and shake. Portion into 8 martini glasses and finish each with a splash of sparkling wine. Garnish with a piece of lemongrass and a skewer of fresh cranberries.